scholarly journals Formulae to Predict Elastic Hoop Stresses across the Transverse Edge of a Large Radial Circular Cross Bore in Thick Cylinders

2020 ◽  
Vol 13 (10) ◽  
pp. 3048
Author(s):  
P. K. Nziu ◽  
L. M. Masu
Keyword(s):  
Hoop Stresses

Bulging bifurcation of inflated circular cylinders of doubly fiber-reinforced hyperelastic material under axial loading and swelling

2015 ◽  
Vol 22 (4) ◽  
pp. 666-682 ◽  
Author(s):  
Hasan Demirkoparan ◽  
Jose Merodio
Keyword(s):  
Potential Benefit ◽  
Arterial Wall ◽  
Axial Loading ◽  
Circular Cylinders ◽  
Orthotropic Materials ◽  
Aneurysm Formation ◽  
Inner Radius ◽  
Fiber Winding ◽  
Hoop Stresses ◽  
Winding Angle

In this paper, we examine the influence of swelling on the bulging bifurcation of inflated thin-walled cylinders under axial loading. We provide the bifurcation criteria for a membrane cylinder subjected to combined axial loading, internal pressure and swelling. We focus here on orthotropic materials with two preferred directions which are mechanically equivalent and are symmetrically disposed. Arterial wall tissue is modeled with this class of constitutive equation and the onset of bulging is considered to give aneurysm formation. It is shown that swelling may lead to compressive hoop stresses near the inner radius of the tube, which could have a potential benefit for preventing aneurysm formation. The effects of the axial stretch, the strength of the fiber reinforcement and the fiber winding angle on the onset of bifurcation are investigated. Finally, a boundary value problem is studied to show the robustness of the results.

Relaxation of Residual Stresses in and around Mechanical Fasteners Due to Fatigue Loading

2006 ◽  
Vol 524-525 ◽  
pp. 153-158 ◽  
Author(s):  
Matthew E. Fox ◽  
Philip J. Withers
Keyword(s):  
Residual Stresses ◽  
Hoop Stress ◽  
Fatigue Cracks ◽  
Fatigue Loading ◽  
Far Field ◽  
Synchrotron Diffraction ◽  
Fastener Hole ◽  
Single Plate ◽  
Mechanical Fasteners ◽  
Hoop Stresses

The residual stresses around clearance-fit mechanical fasteners have been found to be similar to those around cold expanded holes where compressive hoop stresses close to the fastener hole are balanced by far-field tensile stresses. This compressive zone has been shown to prolong fatigue lifetimes around fastener holes. Constant amplitude fatigue loading was applied to single plate rivet specimens for varying numbers of cycles to investigate the redistribution of these stresses after fatiguing. Synchrotron diffraction was used to map the evolution of the residual stresses around the rivets. Little change in the hoop stress local to the rivets occurred until visible fatigue cracks were observed suggesting that relaxation of these stresses is due to the cracks rather than their cause.

A new approach for pre-stressing of rail-end-bolt holes

2016 ◽  
Vol 231 (12) ◽  
pp. 2275-2283 ◽  
Author(s):  
JT Maximov ◽  
GV Duncheva ◽  
IM Amudjev ◽  
AP Anchev ◽  
N Ganev
Keyword(s):  
Fatigue Life ◽  
Fatigue Cracks ◽  
New Technology ◽  
Innovative Technology ◽  
Bolted Joint ◽  
Compressive Stresses ◽  
Process Formation ◽  
Technology Process ◽  
Bolt Holes ◽  
Hoop Stresses

Bolted joint railroad is the subject matter of this paper. Rail joint elements are subjected to cyclic and impact loads as a result of the passage of trains, which causes the origination and growth of fatigue cracks occurring, in most cases, around the bolt holes. Fatigue failure around rail-end-bolt holes is particularly dangerous because it leads to derailment of trains and, consequently, to inevitable accidents. Moreover, the cracking at rail-ends, which starts from bolt hole surface, causes premature rails replacement. The presence of residual compressive hoop stresses around the bolted holes, which is achieved by prestressing of these holes, extends the fatigue life of bolted joint railroads. This article presents an innovative technology for pre-stressing of rail-end-bolt holes, implemented on a vertical machining centre of Revolver vertical (RV) type. Two consecutive operations are involved in the manufacturing technology process: formation of the hole by drilling, reaming and making of a chamfer through a new combined cutting tool; cold hole working by spherical motion cold working through a new tool equipment, which minimizes the axial force on the reverse stroke. The new technology introduces beneficial residual compressive stresses around the bolted holes thereby preventing the fatigue cracks growth and increasing the fatigue life of these openings.

Hydromagnetic winds from accretion disks

1986 ◽  
Vol 64 (4) ◽  
pp. 501-506 ◽  
Author(s):  
Ralph E. Pudritz ◽  
Colin A. Norman
Keyword(s):  
Accretion Disks ◽  
Energy Transport ◽  
Cataclysmic Variables ◽  
Wind Model ◽  
Ionized Gas ◽  
Molecular Outflows ◽  
Self Similar ◽  
Similar Solutions ◽  
Accretion Shock ◽  
Hoop Stresses

We present a hydromagnetic wind model for molecular and ionized gas outflows associated with protostars. If the luminosity of protostars is due to accretion, then centrifugally driven winds that arise from the envelopes of molecular disks explain the observed rates of momentum and energy transport. Ionized outflow originates from disk radii r ≤ 1015 cm inside of which Ly-continuum photons from the protostellar accretion shock are intercepted. Observed molecular outflows arise from the cool disk envelope at radii 1015 ≤ r ≤ 1017 cm. The mass-loss rates of these two component outflows are [Formula: see text] and [Formula: see text]. These winds solve the angular-momentum problem of star formation. We propose that the collimation of such outflows is due to "hoop" stresses generated by the increasingly toroidal magnetic field in the wind and suggest that the structure of the underlying disks makes self-similar solutions for these outflows likely. Finally, we apply this analysis to other accreting systems such as cataclysmic variables.

Modified Equation to Predict Leak/Rupture Criteria for Axially Through-Wall Notched X80 and X100 Linepipes Having Higher Charpy Energy

2004 ◽  
Author(s):  
Shinobu Kawaguchi ◽  
Naoto Hagiwara ◽  
Mitsuru Ohata ◽  
Masao Toyoda
Keyword(s):  
Fracture Toughness ◽  
Flow Stress ◽  
Pipe Material ◽  
Test Results ◽  
Absorbed Energy ◽  
Bending Tests ◽  
Full Scale Tests ◽  
Hoop Stresses ◽  
The Relationship ◽  
Modified Equation

A method of predicting the leak/rupture criteria for API 5L X80 and X100 linepipes was evaluated, based on the results of hydrostatic full-scale tests for X60, X65, X80 and X100 linepipes with an axially through-wall (TW) notch. The TW notch test results clarified the leak/rupture criteria, that is, the relationship between the initial notch lengths and the maximum hoop stresses during the TW notch tests. The obtained leak/rupture criteria were then compared to the prediction of the Charpy V-notch (CVN) absorbed energy-based equation, which has been proposed by Kiefner et al. The comparison revealed that the CVN-based equation was not applicable to the pipes having a CVN energy (Cv) greater than 130 J and flow stress greater than X65. In order to predict the leak/rupture criteria for these linepipes, the static absorbed energy for ductile cracking, (Cvs)i, was introduced as representing the fracture toughness of a pipe material. The (Cvs)i value was determined from the microscopic observation of the cut and buffed Charpy V-notch specimens after static 3-point bending tests. The CVN energy in the original CVN-based equation was replaced by an equivalent CVN energy, (Cv)eq’ which was defined as follows: (Cv)eq = 4.5 (Cvs)i. The leak/rupture criteria for the X80 and X100 linepipes with higher CVN energies were reasonably predicted by the modified equation using the (Cvs)i value.

The Influence of Geometrical Distortions of Three-Dimensional Finite Elements, Used to Model Proximal Femoral Bone

1995 ◽  
Vol 209 (1) ◽  
pp. 31-36 ◽  
Author(s):  
J Vander Sloten ◽  
G van der Perre
Keyword(s):  
Proximal Femur ◽  
Hoop Stress ◽  
Three Dimensional ◽  
Element Model ◽  
Bending Stress ◽  
Different Types ◽  
Dimensional Finite Element ◽  
Middle Node ◽  
Three Dimensional Finite Element ◽  
Hoop Stresses

A realistic three-dimensional finite element model of the proximal femur requires the use of irregularly shaped elements to represent this geometry, unless the geometry is considerably simplified. The authors have investigated the influence of different types of element distortions upon the accuracy of two stresses which are relevant in the proximal femur: the bending stress and the tangential (hoop) stress. While most angular and geometric distortions did not influence the bending stress significantly, the position of the middle node on the edge of a quadratic element was very critical, as were some types of element skewness. The hoop stresses can only be calculated accurately if the geometry is modelled as well as possible by a cylinder, and not by a cone.

Investigation of the Biaxial Behaviour of 316 Stainless Steel Based on Critical Plane Method

2018 ◽  
Vol 774 ◽  
pp. 510-515
Author(s):  
A.S. Cruces ◽  
Pablo Lopez-Crespo ◽  
Belen Moreno ◽  
S. Bressan ◽  
Takamoto Itoh
Keyword(s):  
Stainless Steel ◽  
Hoop Stress ◽  
Axial Stress ◽  
Critical Plane ◽  
316 Stainless Steel ◽  
Dog Bone ◽  
Critical Plane Approach ◽  
Hoop Stresses ◽  
Life Predictions ◽  
Biaxial Behavior

In this work the biaxial behavior of 316 stainless steel is studied under the lens of critical plane approach. A series of ten experiments were developed on dog bone shape hollow cylindrical specimens made of type 316 stainless steel. Five different loading conditions were assessed, with (i) only axial stress, (ii) only hoop stress, (iii) proportional combination of axial and hoop stresses, (iv) non-proportional combination of axial and hoop stresses with square shape and (v) non-proportional combination of axial and hoop stresses with L-shape. The fatigue analysis is performed following four different critical plane theories, namely Wang-Brown, Fatemi-Socie, Liu I and Liu II. The efficiency of all four theories is studied in terms of the accuracy of their life predictions.

Through-Thickness Residual Stress Distribution After the Cold Expansion of Fastener Holes and Its Effect on Fracturing

2004 ◽  
Vol 126 (1) ◽  
pp. 129-135 ◽  
Author(s):  
A. Tamer O¨zdemir ◽  
Lyndon Edwards
Keyword(s):  
Thickness Effect ◽  
Fourier Series Expansion ◽  
Hole Drilling ◽  
Three Dimension ◽  
Stress Distributions ◽  
Element Analysis ◽  
Cold Expansion ◽  
Residual Strains ◽  
Hoop Stresses ◽  
Stress Patterns

Many analytical and experimental techniques utilize two-dimensional analysis approach to determine residual strains and stresses at cold expanded holes. In the present work, a recently developed technique of hole drilling was used to sketch stress patterns in three-dimension at a particular orientation of split-sleeve cold expanded holes. At this orientation, similarities were obtained in between the present results and the stress distributions measured by Fourier series expansion, neutron diffraction methods and prediction of a recent finite element analysis. It is clear that after cold expansion there are significant variations in residual hoop stresses at different sections through the thickness of the plate. However, finish reaming and de-burring around the hole redistributes residual stresses such that hoop stresses adjacent to the hole along its entire length becomes more compressive and almost uniform. Finally a correlation between stress pattern and crack profile, displaying the through-thickness effect was shown.

scholarly journals Cold Expansion Process with Multiple Balls—Numerical Simulation and Comparison with Single Ball and Tapered Mandrels

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5536
Author(s):  
David Curto-Cárdenas ◽  
Jose Calaf-Chica ◽  
Pedro Miguel Bravo Díez ◽  
Mónica Preciado Calzada ◽  
Maria-Jose Garcia-Tarrago
Keyword(s):  
Numerical Simulation ◽  
Finite Element Method ◽  
Finite Element ◽  
Fatigue Life ◽  
Experimental Tests ◽  
The Finite Element Method ◽  
Expansion Process ◽  
Cold Expansion ◽  
Hoop Stresses ◽  
Element Method

Cold expansion technology is an extended method used in aeronautics to increase fatigue life of holes and hence extending inspection intervals. During the cold expansion process, a mechanical mandrel is forced to pass along the hole generating compressive residual hoop stresses. The most widely accepted geometry for this mandrel is the tapered one and simpler options like balls have generally been rejected based on the non-conforming residual hoop stresses derived from their use. In this investigation a novelty process using multiple balls with incremental interference, instead of a single one, was simulated. Experimental tests were performed to validate the finite element method (FEM) models and residual hoop stresses from multiple balls simulation were compared with one ball and tapered mandrel simulations. Results showed that the use of three incremental balls significantly reduced the magnitude of non-conforming residual hoop stresses and the extension of these detrimental zone.

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